Opening Friday around the globe, Avengers: Endgame will not only conclude Phase Three of the Marvel Cinematic Universe, but also wrap up 11 years' worth of storytelling. Although plot details remain scarce, marketing has all but confirmed the heroes return to the Battle of New York from The Avengers. The highly anticipated sequel will no doubt also link back to other, earlier Marvel Studios films that have provided many of the building blocks for what's become called the "Infinity Saga."
Directors Joe and Anthony Russo recently advised fans to re-watch their other MCU films in preparation for Endgame's release: Captain America: The Winter Soldier, Captain America: Civil War and, of course, Avengers: Infinity War. They're connected, we're told, by a thematic thread.
However, those aren't the only movies should brush up on before they settle in for Endgame. In addition to The Winter Soldier, Civil War and Infinity War, here are four other MCU films that may be key to the developments of the Phase Three finale.
The Avengers
Joss Whedon's 2012 film is perhaps one of the most vital of the MCU. Not only did it first bring together Earth's Mightiest Heroes, it satisfyingly capped off Phase One, while setting the stage the future. It established the relationships among the founding Avengers, and it's also where fans caught their first glimpse of the cinematic universe's primary antagonist, Thanos.
As we have seen from Endgame's marketing, the focus will return to the original six: Iron Man, Captain America, Thor, the Hulk, Black Widow and Hawkeye (aka Ronin). More importantly, however, The Avengers might be even more crucial to Endgame's story. Leaked set photos in June 2018 first hinted at a re-creation of the climactic Battle of New York, seemingly confirmed by Endgame's later promos. We have a theory why.
Avengers: Age of Ultron
The 2015 sequel Avengers: Age of Ultron not only solidified the bonds among the heroes, it also set up many storylines: the first hint at friction between Steve Rogers and Tony Stark; the introductions of the Vision and Scarlet Witch, not to mention Wakanda and Ulysses Klaue; and the foreshadowing of the events of Thor: Ragnarok.
Age of Ultron was also crucial to the Infinity Saga. Because of Thor's vision, we learned all about the Infinity Stones. It's also where we discover that Clint Barton has a family, which would appear to drive his story, and transformation into Ronin, in Endgame.
On top of that, Tony Stark's nightmarish vision of his fallen teammates on a cosmic battlefield that appears to Chitauri space, better known as Sanctuary, may provide a glimpse of the events of Endgame. After all, the trailers confirm the Avengers head into space to take the fight to Thanos.
Thor: Ragnarok
The best of the god of thunder's solo films, 2017's Thor: Ragnarok was also a showcase for Bruce Banner and the Hulk. Star Mark Ruffalo described the fan-favorite movie as the first chapter in a "Hulk trilogy" that would conclude with what became Avengers: Endgame.
In Ragnarok, the Hulk was no longer a near-mindless monster; he could speak in short sentences, and he had feelings that went beyond rage. But after his defeat by Thanos in the opening scenes of Infinity War, the Hulk refused to reemerge to help Banner and the Avengers, but the Green Goliath is expected to return in Endgame.
Theories suggest we'll see yet another incarnation of the Jade Giant, one that closely resembles the "Professor Hulk" persona from the comics. If the two distinct personalities at last find common ground, they could unite in a form that possesses Banner's intelligence and disposition, and the Hulk's strength.
Ant-Man and the Wasp
In the grand scheme of things, an Ant-Man film might be easy to overlook. But make no mistake, 2018's Ant-Man and the Wasp might hold the key to victory. At the center of the sequel was the Quantum Realm, a subatomic dimension in which Janet Van Dyne was trapped for decades.
A brief mention of "time vortexes" within the Quantum Realm has fueled many fan theories about Endgame, regarding how the heroes could travel back to the Battle of New York. Even the new red-and-white "team suits," finally confirmed by Endgame trailers, are thought to be used for the excursion into the Quantum Realm.
Directed by Anthony and Joe Russo, Avengers: Endgame stars Robert Downey Jr., Chris Evans, Mark Ruffalo, Chris Hemsworth, Scarlett Johansson, Jeremy Renner, Don Cheadle, Paul Rudd, Brie Larson, Karen Gillan, Danai Gurira, Benedict Wong, Jon Favreau and Bradley Cooper, with Gwyneth Paltrow and Josh Brolin. The film arrives Friday.